Former F1 supremo Bernie Ecclestone has suggested Lewis Hamilton is "not quite the fighter that he was" and believes he could still retire from F1 at the end of the year.
Hamilton trails title rival Max Verstappen by 32 points and has failed to take victory in the last five races in the season the British driver aims to become the first to win an eighth world championship.
Having won six of the last seven championships with Mercedes, Ecclestone hinted that a lack of effort in previous years - where there was little competition - could be contributing to his troubles this year.
"I have spoken to lots of people about this and perhaps Lewis is not quite the fighter that he was," said Ecclestone in an interview with the PA news agency.
"There are lots of occasions this year where he could have done better and he hasn't.
"He hasn't had any competition, the equipment has always been super, and he hasn't really had to make the effort. But now maybe he is thinking that he better take it a bit easier.
"At the beginning of the year, I thought he would look to win the championship and then retire. But it appears not, even though I wouldn't rely too much on contracts. He can escape from that.
"He probably had a look at the clothing range and music but realised that it is not as easy to make money there as it is in F1."
Ecclestone issues warning to Hamilton over Black Lives Matter support
Ecclestone has revealed, however, that he has been in contact with the world champion since then and explained his belief that Hamilton's efforts will eventually leave the Briton with regrets.
"Lewis thought I was against [his campaigning] but he was wrong because I know what he is trying to do," he added.
"He called me because I spoke to his father, Anthony. I said the trouble for Lewis is that he has gone out of his way to wave the flag for Black Lives Matter and that people are making an awful lot of money out of this, and not him.
"As soon as the passion wears off, he will be left with it being his fault. And all he has ever done is try to do something to support it.
"It is the same thing with football where these things have become the fashionable thing to do to make it look as if you are interested in doing something. But I wonder what people actually do apart from talking about it?
"Lewis has done more than most for this. I don't know what the footballers have actually done other than support each other."
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